/* Generic Form Validation Functions */

// if field is empty, will display an alert message
function is_empty(field, alertbox) {
    if (field.value==null || field.value=="") {
        alert(alertbox);
        return false;
    }
    else {
        return true;
    }
}

// Returns true if character c is a letter
// (a..z or A..Z)
function isLetter (c) {
    return ( ((c >= "a") && (c <= "z")) || ((c >= "A") && (c <= "Z")) )
}
       
    
// Returns true if character c is a digit
// (0 .. 9).
function isDigit (c) {
    return ((c >= "0") && (c <= "9"))
}

// Returns true if character c is a letter or digit.
function isLetterOrDigit (c) {
    return (isLetter(c) || isDigit(c))
}